feat: multiple UI improvements, font settings, and memory file display names (#175)

## Summary

- **fix**: `show_thinking_blocks` setting now persists across sessions — it was defined on the TypeScript side but missing from the Rust `HikariConfig` struct, so serde silently dropped it on every save/load
- **feat**: Tool calls are now rendered as collapsible blocks matching the Extended Thinking block aesthetic, replacing the old inline dropdown approach
- **feat**: Add configurable max output tokens setting
- **feat**: Use random creative names for conversation tabs
- **test**: Significantly expanded frontend unit test coverage
- **docs**: Require tests for all changes in CLAUDE.md
- **feat**: Allow users to specify a custom terminal font (Closes #176)
- **feat**: Display friendly names for memory files derived from the first heading (Closes #177)
- **feat**: Add custom UI font support for the app chrome (buttons, labels, tabs)
- **fix**: Apply custom UI font to the full app interface — `.app-container` was hardcoded, blocking inheritance from `body`; also renamed "Custom Font" to "Custom Terminal Font" for clarity

✨ This PR was created with help from Hikari~ 🌸

Reviewed-on: #175
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

src/lib/stores/achievements.test.ts

@@ -0,0 +1,185 @@
+import { describe, it, expect, vi } from "vitest";
+import { get } from "svelte/store";
+import { setMockInvokeResult, emitMockEvent } from "../../../vitest.setup";
+import {
+  achievementsStore,
+  unlockedAchievements,
+  lockedAchievements,
+  achievementsByRarity,
+  achievementProgress,
+  initAchievementsListener,
+} from "./achievements";
+import type { AchievementUnlockedEvent } from "$lib/types/achievements";
+import { playAchievementSound } from "$lib/sounds/achievement";
+
+vi.mock("$lib/sounds/achievement", () => ({
+  playAchievementSound: vi.fn(),
+}));
+
+// Helper to build a minimal unlock event
+function makeEvent(id: AchievementUnlockedEvent["achievement"]["id"]): AchievementUnlockedEvent {
+  return {
+    achievement: {
+      id,
+      name: "Test",
+      description: "Test achievement",
+      icon: "🏆",
+      unlocked_at: null,
+    },
+  };
+}
+
+describe("achievementsStore initial state", () => {
+  it("all achievements start as locked", () => {
+    const state = get(achievementsStore);
+    expect(state.achievements["FirstSteps"].unlocked).toBe(false);
+    expect(state.achievements["GrowingStrong"].unlocked).toBe(false);
+  });
+
+  it("totalUnlocked starts at 0", () => {
+    expect(get(achievementsStore).totalUnlocked).toBe(0);
+  });
+
+  it("lastUnlocked starts as null", () => {
+    expect(get(achievementsStore).lastUnlocked).toBeNull();
+  });
+});
+
+describe("derived stores initial state", () => {
+  it("unlockedAchievements is initially empty", () => {
+    expect(get(unlockedAchievements)).toEqual([]);
+  });
+
+  it("lockedAchievements contains all achievements initially", () => {
+    const locked = get(lockedAchievements);
+    const total = Object.keys(get(achievementsStore).achievements).length;
+    expect(locked.length).toBe(total);
+  });
+
+  it("achievementsByRarity groups achievements into rarity buckets", () => {
+    const byRarity = get(achievementsByRarity);
+    expect(byRarity.common).toBeInstanceOf(Array);
+    expect(byRarity.rare).toBeInstanceOf(Array);
+    expect(byRarity.epic).toBeInstanceOf(Array);
+    expect(byRarity.legendary).toBeInstanceOf(Array);
+    expect(byRarity.common.length).toBeGreaterThan(0);
+  });
+
+  it("achievementProgress shows zero unlocked initially", () => {
+    const progress = get(achievementProgress);
+    expect(progress.unlocked).toBe(0);
+    expect(progress.total).toBeGreaterThan(0);
+    expect(progress.percentage).toBe(0);
+  });
+});
+
+describe("achievementsStore.unlockAchievement", () => {
+  it("marks the achievement as unlocked and updates totalUnlocked", () => {
+    achievementsStore.unlockAchievement(makeEvent("GrowingStrong"));
+    const state = get(achievementsStore);
+    expect(state.achievements["GrowingStrong"].unlocked).toBe(true);
+    expect(state.totalUnlocked).toBe(1);
+    expect(state.lastUnlocked?.id).toBe("GrowingStrong");
+  });
+
+  it("sets unlockedAt from the event's unlocked_at timestamp", () => {
+    achievementsStore.unlockAchievement({
+      achievement: {
+        id: "BlossomingCoder",
+        name: "Blossoming Coder",
+        description: "100k tokens",
+        icon: "🌸",
+        unlocked_at: "2026-01-15T12:00:00.000Z",
+      },
+    });
+    const state = get(achievementsStore);
+    expect(state.achievements["BlossomingCoder"].unlockedAt).toBeInstanceOf(Date);
+  });
+
+  it("does nothing when the achievement is already unlocked", () => {
+    achievementsStore.unlockAchievement(makeEvent("TokenMaster"));
+    const firstTotal = get(achievementsStore).totalUnlocked;
+    achievementsStore.unlockAchievement(makeEvent("TokenMaster"));
+    expect(get(achievementsStore).totalUnlocked).toBe(firstTotal);
+  });
+
+  it("calls playAchievementSound when playSound is true (default)", () => {
+    achievementsStore.unlockAchievement(makeEvent("TokenBillionaire"));
+    expect(playAchievementSound).toHaveBeenCalled();
+  });
+
+  it("does not call playAchievementSound when playSound is false", () => {
+    achievementsStore.unlockAchievement(makeEvent("TokenTreasure"), false);
+    expect(playAchievementSound).not.toHaveBeenCalled();
+  });
+
+  it("logs an error when playAchievementSound throws", () => {
+    vi.mocked(playAchievementSound).mockImplementationOnce(() => {
+      throw new Error("Sound failed");
+    });
+    const consoleSpy = vi.spyOn(console, "error").mockImplementation(() => {});
+    achievementsStore.unlockAchievement(makeEvent("HelloWorld"));
+    expect(consoleSpy).toHaveBeenCalledWith("Failed to play achievement sound:", expect.any(Error));
+    consoleSpy.mockRestore();
+  });
+});
+
+describe("derived stores after unlocks", () => {
+  it("unlockedAchievements includes previously unlocked achievements", () => {
+    const unlocked = get(unlockedAchievements);
+    expect(unlocked.some((a) => a.id === "GrowingStrong")).toBe(true);
+  });
+
+  it("lockedAchievements excludes previously unlocked achievements", () => {
+    const locked = get(lockedAchievements);
+    expect(locked.some((a) => a.id === "GrowingStrong")).toBe(false);
+  });
+
+  it("achievementProgress reflects the current unlocked count", () => {
+    const progress = get(achievementProgress);
+    expect(progress.unlocked).toBeGreaterThan(0);
+    expect(progress.percentage).toBeGreaterThan(0);
+  });
+});
+
+describe("achievementsStore.updateProgress", () => {
+  it("updates the progress value for an achievement", () => {
+    achievementsStore.updateProgress("FirstMessage", 50);
+    expect(get(achievementsStore).achievements["FirstMessage"].progress).toBe(50);
+  });
+});
+
+describe("achievementsStore.reset", () => {
+  it("resets totalUnlocked to 0 and lastUnlocked to null", () => {
+    achievementsStore.reset();
+    const state = get(achievementsStore);
+    expect(state.totalUnlocked).toBe(0);
+    expect(state.lastUnlocked).toBeNull();
+  });
+});
+
+describe("initAchievementsListener", () => {
+  it("unlocks an achievement when the achievement:unlocked event fires", async () => {
+    await initAchievementsListener();
+    emitMockEvent("achievement:unlocked", makeEvent("FirstSteps"));
+    expect(get(achievementsStore).achievements["FirstSteps"].unlocked).toBe(true);
+  });
+
+  it("loads saved achievements from the backend without playing sounds", async () => {
+    setMockInvokeResult("load_saved_achievements", [makeEvent("ConversationStarter")]);
+    await initAchievementsListener();
+    expect(get(achievementsStore).achievements["ConversationStarter"].unlocked).toBe(true);
+    expect(playAchievementSound).not.toHaveBeenCalled();
+  });
+
+  it("logs an error when loading saved achievements fails", async () => {
+    setMockInvokeResult("load_saved_achievements", new Error("Storage unavailable"));
+    const consoleSpy = vi.spyOn(console, "error").mockImplementation(() => {});
+    await initAchievementsListener();
+    expect(consoleSpy).toHaveBeenCalledWith(
+      "Failed to load saved achievements:",
+      expect.any(Error)
+    );
+    consoleSpy.mockRestore();
+  });
+});